Flexible absorbent sheet



Feb. 25, 1964 c w JR 3,122,141

FLEXIBLE ABSORBENT SHEET Filed March 29, 1962 INVENTOR 502 5 A (Pd/ 491k ATTO R N EY United States Patent O 3,122,141 FLEXELE ABSORBENT SIEET George A. Crowe, lira, llainfield, N..l'., assignor to Johnson & Johnson, a corporation of New Jersey Filed Mar. 29, 1%2, Ser. No. 183,435 9 Claims. (Cl. 128-296) The present invention relates to resilient absorbent sheet materials and bandage wraps formed of the same.

Synthetic cellular sponge materials of varying types are presently available on the market. Many of these are quite soft and resilient and make excellent padding materials. However, many of the softer, more flexible and resflient cellular sponge materials, such, for example, as flexible and resilient sponges formed of polyurethane esters and polyurethane ethers, as, for example, described in US. Patent 2,956,310 or other foamable cellular sponge-forming polymeric materials as nylon, rubber, polyethylene, and polyvinyl chloride, are hydrophobic in nature and will not readily absorb fluids with which they are placed in contact. In copending application Ser. No. 159,117, filed December 13, 1961, absorbent sheet materials are described which comprise sheets of resilient, flexible, hydrophobic sponge materials which contain hydrophilic fibers which extend from at least one surface of the sheet of cellular sponge material well down into the main body thereof. These fibers act to draw fluids from the surface of the sponge sheet into the main body thereof as hereinafter more fully described. W'hen the fibers pass completely through the sheet of sponge material, the fibers also act to draw aqeous-base fluids completely through the sponge sheet where the fluids can then be absorbed by any absorbent surface provided on the other side.

These materials may be used for any purpose where a resilient, highly absorbent sheet material is needed. However, materials of this type are particularly useful in the preparation of surgical dressings and the like.

In the treatment of wounds it is generally desirable to protect the wound with a protective covering that will. draw wound exudate away from the wound surface and will, at the same time, form a protective cushion over the wound. Where the Wound is of such nature that there is copious wound exudate, heavy gauze dressings formed of many layers of gauze are generally used in order to remove and absorb such exudate so as to keep the wound area free of the same. Resilient, flexible, synthetic sponge materials of the type referred to when used to cover a wound will provide an excellent cushioning protective cover. However, such materials do not satisfactorily remove fluids from an underlying surface with which they are placed in contact and are, accordingly, unsuitable for use as dressing materials in place of the conventional gauze or other absorbent dressings. By providing in the sheet of synthetic cellular sponge. material numerous hydrophilic fibers extending from the surface of such sponge into the main body thereof, the hydrophilic fibers act to rapidly draw fluids from the surface of the sponge sheet into the cellular sponge material, much of the fluid being deposited in the cellular structure through which the absorbent hydrophilic fibers pass.

Many dressings are used in the form of wraps or bandages. With dressings of this type appreciable pull may be placed on the dressing during application and, accordingly, the dressing should be of suflicient strength to withstand such ulling forces. In accordance with the present invention, cellular hydrophobic sponge-base absorbent dressings are prepared by needling hydrophilic fibers from a web of such fibers through a flexible strengthening sheet into a hydrophobic sponge base. The fibers passing down into the cellular sponge base not only act to draw fluids down into the sponge but also bind the sponge, strengthening sheet and fiber web together.

The sheet of cellular sponge material and the fiber web may extend the full length of the intermediate flexible sheet or the intermediate flexible sheet may extend substantially beyond the web of fibers and the cellular sponge sheet, forming in the latter case a bandage wrap of the flexible sheet material with an absorbent pad formed on one portion thereof. The flexible intermediate sheet may be formed of any suitable flexible sheet material, including sheets of plastic. In the preferred practice of the present invention, the intermediate flexi ble sheet is formed of woven or knitted fabric. If a sheet or sheets of plastic material should be used, however, materials sufficiently elastic as to squeeze the fiber bundles passing therethrough should be avoided, as they tend to interfere with fluid movement along the fiber bundles. Accordingly, sheet rubber is generally unsuitable for the purpose unless the rubber is stabilized around the fiber bundles passing through the same so that the rubber sheet does not squeeze the fibers and restrict fluid movement. Elastic fabrics, however, can be used as there is generally not suflicient squeeze with such fabrics to substantially restrict fluid movement along the bundles of needled fibers. There is no particular problem with the conventional elastic woven or knitted fabrics.

In making the absorbent cellular sheet materials of the present invention, flexible sheet, which may comprise either a fabric or a plastic sheet of suflicient tensile strength to serve as a bandage Wrap, is placed on one surface of a sheet of cellular sponge material and a web of hydrophilic fibers is then formed or placed over the same. The sponge with the flexible sheet and fiber web thereon is then needled by passing barbed needles down through the web of fibers and flexible sheet into the sponge to force a portion of the fibers through the main body of the underlying sponge. These fibers passing from the fiber Web down into the sheet sponge material not only serve to draw fluid into the sponge body but also serve to mechanically interlock the absorbent fiber layers with the cellular sponge sheet and firmly anchor both the fiber web and the cellular sponge to the intermediate flexible sheet. Where the needled fibers pass completely through the sheet of cellular spong material, even though the sponge material itself may be fairly strongly hydrophobic in nature, aqueous-base fluids which contact the side of the sponge sheet opposed to the side containing the fiber layer are rapidly drawn up into and through the sheet of sponge material. Some of the fluid remains in the cells in the sponge material adjacent the needled fibers passing through the same. However, most of the fluid is drawn on through the sponge and spread laterally through the web of hydrophilic fibers on the sponge surface. Where the fibers pressed into the cellular sponge sheet by the needle operation pass down into the sheet but do not pass all the way through, it is found that when fluid is placed on the surface of the sponge sheet containing the web of hydrophilic fibers, that not only do the webs of hydrophilic fibers act to absorb the fluid but that the fibers that penetrate down into the cellular sponge sheet carry a substantial amount of fluid down into the cells of the sponge material, thus substantially increasing the over-all absorptive capacity of the resulting product. Where the cellular sponge sheet is of hydrophobic material, the opposite side to that containing the Webs of hydrophilic fibers can be wetted without any fluid passing through the product and wet ting the fiber webs contained on the other side. The product thus prepared has both the advantages of a highly absorbent fabric as well as those of a waterrepellent sheet.

For the hydrophilic fibers, any hydrophilic fibers may be used that can be placed in the cellular sponge sheet so as to extend from a surface of the sheet down into the sponge body. In using the term hydrophilic fibers, those fibers or filaments, including continuous filaments, are included which have the natural property of moving aqueous fluids along their length by capillary action, either as singlerfibers or as fiber bundles, as well as these fibers and filaments which, although normally are not wetted by water, have been treated so as to make the same readily wettable so that they will move aqueous fluids along their surface. It is generally preferred to use cellulosic fibers, such as the natural cellulosic fibers including cotton, ramie, jute, hemp, andbagasse, and the synthetic cellulosic' fibers, such as those formed of regenerated cellulose and cellulose acetate.

Any cellular, hydrophobic sponge material may be used that'is sufficiently flexible and resilient for the purpose intended. It is generally preferred to usesponges formed of polyurethane polyesters, polyurethane polyethers, nylon, polyethylene, rubber, polyvinyl chloride, and formalinized polyvinyl alcohol, or other materials which will remain resilient and flexible without the need of added plasticizers. However, the invention is not limited thereto, and plasticized sponges may be used in practicing the'same. In general, particularly where the material is to be used for surgical dressings, the sponge should be readily flexible and conforming in sheets of about & to 1 inch thickness and'should be soft and resilient in nature. The material should be sufficiently flexible and conforming to fit over body contours and be sufficiently soft and resilient to act as a protective cushion without irritation, as would a stiff sponge structure. Accordingly, it is generally desired that the sponge material, where the products of the present invention are to be used in dressings, have a flexibility of 17-74 percent of original thickness and a resiliency of 78 -98 percent of original thickness. The flexibility and resiliency are measured in the following manner: The original thickness is measured with a micrometer having a dead weight of 56.7 grams per square inch of sample. A 500 gram weight is added, and the thickness is read after 60 seconds to find flexibility. The 500 gram weight is removed and after 60 seconds the thickness is read to find resiliency. Results are expressed in terms of percentage of original thickness.

Although the present invention is not limited to the use of sponge materials that have an open cellular structure, and sponge materials having closed cellular structures may be employed, it is generally preferred that the cellular sponge material used have sufficient open cells that the same will not restrict the passage of air therethrough. Where the sponge material has such open and connecting cellular structure, air can readily reach the surface of a wound to help in the healing of the same. This is particularly important where the fibers which penetrate down into the sponge material do not pass all the way through the sponge material.

In order to further illustrate the invention, reference is made to the drawings wherein are set forth by way of illustration and example certain embodiments thereof.

Referring to the drawings:

FIG. 1 is a perspective view of a bandage strip formed of the present invention;

FIG. 2 is an enlarged view taken along FIG.- a d FIG. 3 is a perspective view of a different type of bandage strip of the present invention.

Referring to FIG. 1, the absorbent sheet is a composite laminate in which 11 is a flexible sheet of cellular sponge material and 12 is a web of relatively long hydrophilic fibers, such, for example, as cotton or rayon textile fibers. Some of the fibers of the fiber web 12 have been forced down through the sheet 11 of sponge material. These fibers or fiber bundles 13 extend on down through line ,2 2 of t1 the sponge sheet 11 and extend slightly through the 0pposite surface 14 as illustrated at 15. Between fiber web 12 and sponge sheet 11 is a sheet of woven fabric 16. The fibers used in forming the fiber web 12 preferably have a fiber length of about 1 inch to 3 inches and a denier of about 1 to 10. vThe fibers of web 12 are pushed down into the sponge sheet 11 through the use of needles containing barbs thereon which catch the fibers and force the same down through the intermediate fabric sheet 16 and the sponge sheet in somewhat of a U configuration, as best illustrated in FIG. 2. It is generally preferred that there be at least about 50 needle penetrations per inch. The downwardly extending fibers 13 not only serve to lock the fiber webs 12 and fabric sheet 16 onto the sponge sheet 11 but also act to draw fluid into the sponge body so as to fill adjacent sponge cells.

With an absorbent sheet structure such as illustrated in FIG. 1, when the side 14 opposed to the side which carries the fiber web 12 is contacted by an aqueous-base fluid, the protruding ends 15 of the fibers are wetted by the fluid and draw the fluid into the sponge sheet even though the sponge material itself is nonabsorbent in nature. In passing through the sponge sheet some of the liquid flows into the adjacent cells, as previously indicated, while other liquid is conducted completely through the sponge sheet and absorbed in the fiber layer 12 and, where the intermediate fabric 16 is absorbent, also in the fabric.

When used as a bandage wrap, either the side 1 or the side containing the fiber web 12 may be placed adjacent the patients skin. Where the side 14 is placed against the patients skin, body exudate, such as perspiration and wound secretions, is rapidly drawn by the fiber ends 15 and fibers 13 up into the body of the sponge 11 and into the absorbent web 12.

As fluids are rapidly drawn into the sponge sheet away 7 from the surface of the skin and as air can pass through the dressing, both by way of the fibers 13 and because of the porous nature of the sponge material itself where such material is used, the skin under the bandage wrap is kept relatively dry and, at the same time, the dressing itself in contact with the skin feels relatively dry as compared with the conventional gauze bandages where the whole undersurface of the dressing becomes wetted and ear- In the embodiment of the invention illustrated in FIG. 3, the fiber web 12 and the cellular sponge sheet 11 are substantially smaller than the intermediate fabric 16 with the result that the fabric extends beyond the absorbent sheet 10 to give free fabric ends 17 and 13. As a result, in this particular modhfication the absorbent sheet portion 10, which in construction is identical to the absorbent sheet illustrated in FIGS. 1 and 2, is in the form of an absorbent, resilient pad firmly affixed to a bandage wrap of fabric. In use, the pad of absorbent sheet 18 would be placed over the injured area and the fabric ends 17 and 13 would then be wrapped around the member containing the injury to hold the pad or dressing portion in place. i

The following specific example with respect to the manufacture of an absorbent product of the type illustrated by FIG. 1 will help to further explain the invention.

The example, however, is given for the purpose of illustration only and the invention is not limited thereto.

Example 3 fibers having a denier of 3 and a fiber length of 1%; inches is placed on top of the fabric sheet.

The sheet of polyurethane foam with the fabric sheet and fiber web is passed through a needling machine, each needle having 9 barbs. The needles are made to penetrate the foam sheet and web from the surface containing the web, the barbs on the needles being in such position as to draw fibers down through the foam sponge sheet, the fibers not extending more than A inch from the other surface. The needling is carried out to give 144 needle penetrations per square inch.

The product so prepared has a woven fabric sheet contained between a web of fibers and the sponge sheet, With fiber bundles extending from the fiber web which just penetrate the opposite surface of the sponge sheet and act to bond the whole together and draw fluids into the same. The product is flexible, resilient, highly absorbent, and has excellent tensile strength.

Red-colored, aqueous-base fluid is placed on the side of the product opposite that containing the web of rayon fibers. The fluid is rapidly drawn up into the sponge sheet and spread through the web of rayon fibers. When the absorbent sheet product is cut through the center and examined, it is seen that fluid is also deposited in many of the cells in the sponge adjacent the rayon fibers which pass therethrough.

In describing the present invention, certain embodiments have been used, including the presently preferred embodiments, to illustrate the invention and the practice thereof. However, other embodiments and modifications within the spirit of the invention will readily occur to those skilled in the art on reading the same. The invention is, accordingly, not to be limited to the specific embodiments illustrated, these embodiments being used for illustration only, but is to be limited only in accordance with the claims appended hereto.

I claim:

1. An absorbent laminate structure having at least one surface composed of aqueous-base fluid absorbing and aqueous-base fluid nonabsorbing areas comprising a flexible sheet contained between a web of hydrophilic fibers and a flexible sheet of cellular hydrophobic sponge material, fibers from said web of fibers extending through said intermediate flexible sheet and through said sheet of cellular sponge material to the opposite surface of said sponge sheet, whereby when the fibers extending through to the opposite surface of said cellular sponge sheet are wetted fluid is drawn up through said sponge sheet by said fibers and dispersed in said fiber web.

2. An absorbent laminate structure of claim 1 in which said intermediate flexible sheet is a woven fabric.

3. An absorbent laminate structure of claim 1 in which said intermediate flexible sheet is a knitted fabric.

4. An absorbent laminate structure of claim 1 in which said intermediate flexible sheet is an elastic fabric.

5. An absorbent laminate structure of claim 1 comprising a bandage wrap in which said intermediate flexible sheet is the form of a flexible strip, such strip extending beyond said fiber web and said sponge sheet, said fiber web being positioned on said sheet at a distance from at least one end thereof, the portion of said flexible intermediate sheet extending beyond said fiber Web and said sponge and being available for wrapping around an injured member.

6. An absorbent laminate structure of claim 5 in which said intermediate flexible sheet strip has both of its ends extending beyond said fiber web and sponge.

7. An absorbent laminate structure of claim 6 in which said intermediate flexible sheet is a woven fabric.

8. An absorbent laminate structure of claim 6 in which said intermediate flexible sheet is a knitted fabric.

9. An absorbent laminate structure of claim 6 in which said intermediate flexible sheet is an elastic fabric.

References Cited in the file of this patent UNITED STATES PATENTS 2,077,514 Callahan Apr. 20, 1937 2,429,486 Reinhardt Oct. 21, 1947 2,811,154 Scholl Oct. 29, 1957 3,025,854 Scholl Mar. 20, 1962 3,033,201 Olsen May 8, 1962 

1. AN ABSORBENT LAMINATE STRUCTURE HAVING AT LEAST ONE SURFACE COMPOSED OF AQUEOUS-BASE FLUID ABSORBING AND AQUEOUS-BASE FLUID NONABSORBING AREAS COMPRISING A FLEXIBLE SHEET CONTAINED BETWEEN A WEB OF HYDROPHILIC FIBERS AND FIBERS FROM SAID WEB OF FIBERS EXTENDING THROUGH SAID INTERMEDIATE FLEXIBLE SHEET AND THROUGH SAID SHEET OF CELLULAR SPONGE MATERIAL TO THE OPPOSITE SURFACE OF SAID SPONGE SHEET, WHEREBY WHEN THE FIBERS EXTENDING THROUGH TO THE OPPOSITE SURFACE OF SAID CELLULAR SPONGE SHEET ARE WETTED FLUID IS DRAWN UP THROUGH SAID SPONGE SHEET BY SAID FIBERS AND DISPERSED IN SAID FIBER WEB. 